Power-operated bending machine



y 25, 1965 c. s. HILTON 3,184,951

POWER-OPERATED BENDING MACHINE Filed Oct. 24, 1961 i FIG.I (24 e 5o-- I2 I 'i 23 FIG 2 l1 :3 l I4, I I? II I u \Q g I 4 '2; a; a 36 i 3 (j 28 MANUAL COTROL 3| SWlTCHES IN V EN TOR.

United States Patent 3,184,951 POWER-OPERATED BENDING MACHINE Clarence Gray Hilton, 269 Maple St., Lynn, Mass. Filed Oct. 24, 1961, Ser. No. 147,321 3 Claims. (Cl. 72-453) This invention comprises a manually-controlled p weroperated machine for precision bending metal strips or bars. The machine is herein shown, by way of example, as organized for bending strip steel stock with extreme accuracy to the predetermined contour of patterns furnished by shoe manufacturers for making cutting dies.

In cutting out vamps, quarters, tips and other shoe upper parts from sheet material shoe manufacturers in general employ clicking presses which require for their operation dies in the form of open frames sharpened on one or both edges and conforming accurately to the exact contour of the blank to be cut from a skin of upper leather or textile sheet. Such dies are usually made from strip steel to 1%" in width and wider for sole cutting dies. The operation of bending such stock to pattern requires a high degree of skill and considerable physical strength. A further difiiculty is encountered in that the ends of the conformed strip must be welded without showing any irregularity in the required contour of the die.

An object of the present invention is to provide a machine having bending tools movable toward and from each other by power means .but being under finger tip control in their action. The operator is thus relieved of all physical exertion in bending the die stock and can devote his whole attention to observing and controlling the effect of each individual operative stroke of the bending tools and the delicate task of presenting and feeding the stock progressively to the action of the bending tools.

These desirable results and others of importance are secure in accordance with the present invention in a bending machine having a flat supporting structure from which projects a fixed bending tool and in which is guided a cooperating movable tool actuated by a fluid pressure system under immediate and sensitive control of the operator.

Preferably and as herein shown the fluid pressure system is of two stage type designed to provide retraction of the movable bending tool under low pressure actuation while the positive operative stroke of the tool is effected under substantially higher actuating pressure. This arrangement contributes largely to the desired sensitive control by the operator of the amount and direction of curvature imparted by each stroke of the tool to the interposed die stock.

Another feature of the invention consists in locating the bending tools on one side of the flat supporting structure and the operating fluid pressure cylinder on the other side so that entire operating stress is self contained in the solid structure of the machine. This feature also facilitates a very compact arrangement of the elements of the machine.

Another feature of the invention resides in the combination of means for supplying by compressed air fluid such as oil under high pressure for effecting the working stroke of a bending tool and oil under relatively low pressure for effecting the retracting stroke of the tool. As herein shown a compressed air cylinder is utilized for two functions, viz, (1) to transfer oil by direct low pressure from an oil reservoir to the tool-retracting end of a double acting cylinder, and (2) to operate a high pressure cylinder acting to transfer oil at high pressure to the tool-advancing end of the double acting cylinder. In practice a pressure of 8000 p.s.i. has been found entirely satisfactory for retracting the tool, while a pres- 3,184,951 Patented May 25, 1965 sure of about 38,000 psi. is readily available for the working stroke.

These and other features of the invention will be best understood and appreciated from the following description of a preferred embodiment thereof, selected for purposes of illustration and shown in the accompanying drawings, in which:

FIG. 1 is a plan view of the machine, and

FIG. 2 is a view in elevation in which certain parts are diagrammatically shown.

The machine herein shown has a solid flat supporting structure upon which the strip die stock may be placed in edgewise position and fed to the die bending tools. The supporting structure includes a table 10 fitted to and lying flush with a base plate 11 and an underlying bottom plate 20 keyed to the base plate by a key 21 and bolted permanently thereto.

A stationary bending tool 12 having a cylindrical shank 13 fitted into the base plate projects upwardly and presents a convex operating face shown as directed toward the right in the drawings. The base plate is recessed to receive a slide 14 arranged to reciprocate in a guideway between gibs 15 and 16 and connected at its outer end to a short link 17. That link in turn is connected to the upper end of a double lever 18 pivoted at 19 to the bottom plate 20. The whole supporting structure is mounted at convenient height upon a frame or casing 22 having an opening for the passage of the upper end of the lever 18.

The slide 14 carries an upwardly projecting bracket 23 and in this is mounted the cooperating concave bending tool or die 24. This tool has a V-shaped recess in its operative face into which the die stock is bent or bowed about an axis perpendicular to the plane of the table 10 when the slide 14 is advanced. It will be apparent that both tools may be readily replaced by others of different contours required or convenient for imparting special formations to the die stock. In FIG. 1 the die stock 50 is represented asbeing shaped into a die for cutting insoles or similar sole pieces.

The double lever 18 is arranged to be rocked by movement of the piston 25 of a double acting fluid pressure cylinder 26 herein shown as bolted to the under face of the the bottom plate 20. The piston 25 is connected to the lower end of the lever 18 through the medium of a link 27. The links 17 and 27 together with the lever 18 therefore constitute an operating train that extends about one end of the supporting structure with the result that stresses developed in operation between the cylinder 26 and the fixed bending tool 12 are all self contained within the supporting structure.

The right hand end of the cylinder 26 may be termed its tool-retracting end and to this is connected a pipe 28 running to the bottom of an oil reservoir 29. From the top of the oil reservoir leads another pipe 30 having a solenoid-operated valve 31 therein with one branch running from a compressed air line 32 and another branch 37 running to the lower end of a compressed air cylinder 34. The cylinder 34 constitutes the first or low pressure stage of a two stage fluid pressure system that includes a high pressure or second stage cylinder 35 directly connected to the cylinder 34. The high pressure cylinder 35 is connected through an oil pipe 36 to the left hand or tool advancing end of the operating cylinder 26.

The compressed air line 32 is connected above the valve 31 and its operating solenoid 33 to the upper end of the cylinder 34 and through a branch 37 and valve 38 to the lower end of the cylinder 34. The valve 38 is operated by a solenoid 39 and both solenoids are included in an electrical circuit controlled by a switch 40 located on the frame, 22 adjacent :to the bending tools and in convenient position for manual control by one hand of the operator,

leaving the other hand free to manipulate the die stock 50. The electric circuit also includes apedal-controlled and the valve 31 closed. Compressed airtis then admitted to the lower end of the cylinder'64, its piston .is advanced building up a pressure of approximately 8000 pounds and this is transmitted through the oil pipe 36 to the piston of the operating cylinder 26 where it is augmented to an oil pressure of approximately 38,000 p.s.i. and the. bending tool 24 advanced in its working stroke towardthe stationary. bending tool 12. So long as the button'of the switch 40 is depressedthe tool- 24'Will continue to ad- Vance under powerful pressure to the full limit of its strokeand the interposed die -stock,will have imparted .to it a curvature of increasing convexity.

Upon-releasing the button of the switch 40 the valve 38 closes. and the valve 31 opens. air is admitted :to the upper end of the cylinder 34 and its piston retracted, compressed air flows to the top of the reservoir 30 forcing oil under low pressure to the right hand end of the operating cylinder 26. thus movingits piston to the left, retracting the bending tool 24 and forcing oil-from the cylinder 26back into the high pressure cylinder 35.

The structure above described is remarkably quick in its reaction to allthe operators control steps, the mechanical response to either start or stop being within forty microseconds. 'It has the further advantage of utilizing oil under. pressure on both sides of the piston 25 of the double-acting cylinder 26, thus avoiding air leakage which has been found troublesome when air] and oil have been employed on opposite sides of, a plunger or piston.

The compressed air line 32 is shown as including :a gauge, a relief valve, water separator and to these may be added any other instruments or accessories useful in maintaining the system in condition for its required performance.

Having thus disclosed my invention and described in detail :anillustrative embodiment thereofI claim as new and desire to secure by Letters Patent- 1.. In av fluid pressure operated.bending-machine, means Thereupon compressed for actuatinga bending tool comprising a double acting cylinder, an oil reservoir connected to the tool-retracting end thereof, a compressed aircylinder connected to the reservoir for transferring oil therefrom under pressure to the said tool-re-tractingend, and a high pressure cylinder operated by .the.-compressed aircylinder. for transferring oil under. high pressure to the tool advancing end of saiddouble-acting cylinder, whereby the said cylinder is operated in both directions under oil pressure.

2. In a fluid operated bending machine, means-for reciprocating a work-bending tool, comprising a doubleacting'cylinde-r having a piston connected-to the. tool, an oil reservoir connected. to the tool-retracting end of the cylinder, :a compressed air cylinder having connections with the reservoir for transferring oiltherefrom under air pressure to the tool-retracting end of the said doubleacting cylinder, and a high pressure cylinder. having an oil pipe connection with the other end of the doubleacting cylinder for imparting a power movement to the bending tool and at the same time returning oil from the double-acting cylinder to said oil reservoir, whereby the said cylinder is operated in both directions by oil pressure.

a 3. A bending machine as described in claim 2, fur- I ther characterized in that electrically operated valves are provided'zfor simultaneous operation at opposite ends of the said compressed air cylinder forreciprocating a piston therein and for admitting compressed air to the oil reservoir during the reverse movement of the piston.

References Cited bythe Examiner UNITED STATES PATENTS 1,082,793 12/30 Blount. 1,812,816 6/31 Weaver -54.5 1,828,874 10/31 .Myers 60 -545 1,912,828; 6/33 Countryman 153-32 XR' 1,945,8793 2/34 Burger. 2,319,915 5/43 Bolston 153-.43 2,453,929 11/48 OHarah, 60-545 2,668,571 2/54 Leskiewicz 153.48 2,959,205 11/60. Day 15321 XR FOREIGN PATENTS 305,783 5/55 Switzerland.

CHARLES W. LANHAM, Primary Examiner. 

1. IN A FLUID PRESSURE OPERATED BENDING MACHINE, MEANS FOR ACTUATING A BENDING TOOL COMPRISING A DOUBLE ACTING CYLINDER, AN OIL RESERVOIR CONNECTED TO THE TOOL-RETRACTING END THEREOF, A COMPRESSED AIR CYLINDER CONNECTED TO THE RESERVOIR FOR TRANSFERRING OIL THEREFROM UNDER PRESSURE TO THE SAID TOOL-RETRACTING END, AND A HIGH PRESSURE CYLINDER OPERATED BY THE COMPRESSED AIR CYLINDER FOR TRANSFERRING OIL UNDER HIGH PRESSURE TO THE TOOL ADVANCING END OF SAID DOUBLE-ACTING CYLINDER, WHEREBY THE SAID CYLINDER IS OPERATED IN BOTH DIRECTIONS UNDER OIL PRESSURE. 